AOL doesn't block on domain - if there is any blocking, it's based on IP address, so it could be due to a number of things (in other words; they're probably not blocking your domain; they're blocking one or more of our servers for one reason or another). We have gotten some of AOL's warning emails (unfortunately, they're not very specific, and their postmaster team is not always that helpful as far as providing more specific information). From what I can tell, they're not blocking our whole IP range, which is a good thing.
I will say that the way their spam reporting system works (in terms of member complaints) isn't smart enough to determine when the Received chain is legitimate; i.e., if spam is sent to an AOL account because a DH customer forwards mail at their domain through our servers, it still views us as the source. I don't know a really good way around this other than preventing our customers from forwarding email to their AOL accounts.
I'm out of town right now, so please have send a message to support for attention of Jeff C.
With regard to support, support at dreamhost dot com will get your message to the right place, or send a message via the sales form.